A conventional infrared sensor device includes an infrared sensor element and a circuit substrate for mounting this infrared sensor element is conventionally. In this device, a membrane as a thin wall portion is formed on the surface side of the substrate by forming a concave portion on the rear face side of the substrate. The infrared sensor element has an electrode for detection on the surface side of the substrate, and also has an infrared ray absorbing film in the membrane.
FIG. 8 is a view showing an entire schematic sectional construction of such a conventional infrared sensor device. FIG. 9 is a top view of the infrared sensor element 30 and the circuit substrate 20 in the infrared sensor device shown in this FIG. 8.
In the infrared sensor device shown in FIGS. 8 and 9, the concave portion 38 is formed from the rear face 31b side in the substrate 31 constructed by a silicon substrate, etc. in the infrared sensor element 30. Thus, the membrane 33 as a thin wall portion is formed on the surface 31a side of the substrate 31.
The unillustrated electrode for detection constructed by a thermocouple, etc. is formed on the surface 31a of the substrate 31. The infrared ray absorbing film 36 for absorbing the energy of an infrared ray by receiving the infrared ray is formed on this electrode for detection.
The infrared sensor element 30 is mounted onto the circuit substrate 20, and is adhered and fixed to the circuit substrate 20 through an adhesive 22 in a circumferential portion of the membrane 33 on the rear face 31b side of the substrate 31, i.e., in a thick wall portion. The surface 31a of the substrate 31 and the circuit substrate 20 in the infrared sensor element 30 are wired and electrically connected through a bonding wire 50.
Thus, the circuit substrate 20 laminating the infrared sensor element 30 therewith is mounted and fixed to a stem 10 through an adhesive 13. A cap 60 is attached to the stem 10 so as to protect this laminating body. An infrared ray transmitting filter 70 for transmitting only the infrared ray is arranged in this cap 60.
A lead pin 11 is arranged around the circuit substrate 20 in the stem 10. The circuit substrate 20 and the lead pin 11 are electrically connected through the bonding wire 50. Thus, the circuit substrate 20 and the exterior can be electrically connected through the lead pin 11.
[Patent Literature 1]
JP-A-2003-270047
In the conventional infrared sensor device, as mentioned above, the infrared sensor element 30 is adhered to the circuit substrate 20 through the above adhesive 22 in the circumferential portion of the membrane 33 on the rear face 31b side of the substrate 31.
In such a case, the space within the concave portion 38 located below the membrane 33 becomes a sealing space sealed by the adhesive 22 and interrupted from the exterior.
When such a sealing space is formed, the volume within this sealing space is expanded when heat is applied to the infrared sensor element 30, etc. As its result, there is a fear that the membrane 33 having comparatively small strength within the infrared sensor element 30 is broken.
Therefore, it is necessary to set a construction for partially arranging the adhesive 22 adhering the infrared sensor element 30 and the circuit substrate 20 (see the above patent literature 1), and arrange a hole of air extraction in the infrared sensor element 30 so as not to set the space within the concave portion 38 located below the membrane 33 to the sealing space. Therefore, it takes much time and labor to mount the infrared sensor element 30 to the circuit substrate 20.
Further, in the conventional infrared sensor device, as mentioned above, the surface 31a of the substrate 31 and the circuit substrate 20 in the infrared sensor element 30 are connected through the bonding wire 50.
Therefore, as shown in FIG. 9, it is necessary to secure a space for the wire bonding, i.e., a distance D required in the wire bonding. It is correspondingly difficult to make the circuit substrate 20 compact.